Resilient behavior characterization of geomaterials for pavement design

Abstract

Resilient modulus (MR) test and the California Bearing Ratio (CBR) test have been the two most common tests for laboratory characterization of geomaterials, i.e., fine-grained subgrade soils and unbound aggregate materials for road and airfield pavements analysis. However, there is a major difference between the two tests in terms of materials properties. Whereas CBR test evaluates the potential strength of geomaterials, resilient modulus is a stiffness property obtained under repeated/cyclic load test. The determination of resilient modulus requires sophisticated equipment and skilled personnel for laboratory and field testing. Therefore, some agencies continue to use CBR to estimate resilient modulus for flexible pavement design. In this paper, two well-known MR-CBR empirical models were investigated for predicting resilient modulus of fourteen subgrade soils for the analysis and design of a new runway at a commercial airport in the United States. Repeated load and CBR tests were conducted in the laboratory on the subgrade samples to obtain MR and CBR data to develop the empirical models. The results suggest that constitutive models obtained directly from laboratory test data would be more appropriate to characterize the resilient behavior of subgrade soils a high reliability design of runways than empirical correlation models